[Rd] setMethod("Logic", ...)

Robin Hankin r.hankin at noc.soton.ac.uk
Mon Sep 4 10:41:46 CEST 2006

Professor Ripley

thank you for this (and indeed thank you for solving my earlier
problem on octonions).

I still don't know how  to force logic operations on brob objects to  
give an error.

06, at 16:45, Prof Brian Ripley wrote:

> Accordng to the S4groupGeneric page, there is no such group.
> My guess as to why:
> Those operators are not S3 generic in R, and S4 dispatch is piggy- 
> backed
> on S3 dispatch (not necessarily, but for convenience).

I have been trying to use the  example on p119 of S Programming as
a template:

          representation = representation 
          prototype      = list(x=numeric(),positive=logical())

.logicBrob <- function(e1,e2){
   stop("No logic currently implemented for Brobdingnagian numbers")

setMethod("Logic",signature(e1="brob"), .logicBrob)
setMethod("Logic",signature(e2="brob"), .logicBrob)

but this does not work as desired (setMethod() gives an error).  I want,
for example,

!new("brob", x=1:10,positive=rep(T,10))

to call .logicBrob() and report an error.

Robin Hankin
Uncertainty Analyst
National Oceanography Centre, Southampton
European Way, Southampton SO14 3ZH, UK
  tel  023-8059-7743

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